Charge nematicity and electronic Raman scattering in iron-based superconductors

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• 作者：Yann Gallais ; ^{yann.gallais@univ-paris-diderot.fr" class="auth_mail" title="E-mail the corresponding author} ; Indranil Paul ; ^{indranil.paul@univ-paris-diderot.fr" class="auth_mail" title="E-mail the corresponding author}
• 关键词：Iron-based superconductors ; Raman scattering ; Nematicity
• 刊名：Comptes Rendus Physique
• 出版年：2016
• 出版时间：January-February 2016
• 年：2016
• 卷：17
• 期：1-2
• 页码：113-139
• 全文大小：2683 K

文摘

We review the recent developments in electronic Raman scattering measurements of charge nematic fluctuations in iron-based superconductors. A simple theoretical framework of a d-wave Pomeranchuk transition is proposed in order to capture the salient features of the spectra. We discuss the available Raman data in the normal state of 122 iron-based systems, particularly Co-doped BaFe₂As₂, and we show that the low-energy quasi-elastic peak, the extracted nematic susceptibility and the scattering rates are consistent with an electronic-driven structural phase transition. In the superconducting state with a full gap, the quasi-elastic peak transforms into a finite-frequency nematic resonance, evidences for which are particularly strong in the electron-doped systems. A crucial feature of the analysis is the fact that the electronic Raman signal is unaffected by the acoustic phonons. This makes Raman spectroscopy a unique probe of electronic nematicity.